'97 K1500 Suburban stalling after long drive

[denhamt1983]

Hi, first time OBS owner, longtime fan. 1997 K1500 Suburban 5.7L, 250000 miles. Had an issue yesterday that I could use a hand with. I've owned the truck for about 2 months now and had a couple issues with hard starts, like if I ran a bunch of errands then let it sit for 30 mins or so would be pretty tough to get started, worse on a full tank it seemed. Went away after driving it for a couple of weeks, tho, so chalked it up to PO leaving it parked for a while before I bought it. Had a similar problem after a 2 or so hour drive once, but not so bad and once it started no problem.

Yesterday we took her on a camping trip, fully loaded and full tank of gas. Drove about 30 miles/1 hour to where our offroad part of the trip started, crossing one minor mountain pass on the way, all good. Drive about 10 miles back offroad, easy forest service road level stuff. Get to going up the first real hill of this part, moderately steep, and had to stop on the incline to go scout a snow situation up ahead and while I was gone my wife says it just went from running perfect to sputtering, then quickly died. When I reached the truck it was dead, and did the whole hard start thing, but was a PAIN to keep running, just constantly cutting off. Got it turned around, and coming back down cut up a little, but eventually smoothed out and did fine. Cut up a little at highway speed after pulling the mountain pass again, but eventually chilled out and did the last 20 miles or so to town no issues

The PO says he replaced the fuel pump within the last 6 months or so, so it SHOULD be good. I did get a service engine light, but get one intermittently anyway from an exhaust leak so could just be that. Any advice on where to start troubleshooting? Thanks a ton!

 

[RawbDidIt]

Hi, first time OBS owner, longtime fan. 1997 K1500 Suburban 5.7L, 250000 miles. Had an issue yesterday that I could use a hand with. I've owned the truck for about 2 months now and had a couple issues with hard starts, like if I ran a bunch of errands then let it sit for 30 mins or so would be pretty tough to get started, worse on a full tank it seemed. Went away after driving it for a couple of weeks, tho, so chalked it up to PO leaving it parked for a while before I bought it. Had a similar problem after a 2 or so hour drive once, but not so bad and once it started no problem.

Yesterday we took her on a camping trip, fully loaded and full tank of gas. Drove about 30 miles/1 hour to where our offroad part of the trip started, crossing one minor mountain pass on the way, all good. Drive about 10 miles back offroad, easy forest service road level stuff. Get to going up the first real hill of this part, moderately steep, and had to stop on the incline to go scout a snow situation up ahead and while I was gone my wife says it just went from running perfect to sputtering, then quickly died. When I reached the truck it was dead, and did the whole hard start thing, but was a PAIN to keep running, just constantly cutting off. Got it turned around, and coming back down cut up a little, but eventually smoothed out and did fine. Cut up a little at highway speed after pulling the mountain pass again, but eventually chilled out and did the last 20 miles or so to town no issues

The PO says he replaced the fuel pump within the last 6 months or so, so it SHOULD be good. I did get a service engine light, but get one intermittently anyway from an exhaust leak so could just be that. Any advice on where to start troubleshooting? Thanks a ton!

Intermittent, mostly under heavy load? I'd start with the EGR system. There's plenty of other possibilities though, PO may have replaced the fuel pump, but maybe it's not a quality unit, or maybe the tank wasn't cleaned when the new one was installed. Maybe he didn't replace the filter. Could be a vacuum leak, or fuel pressure issue. Best way to tell us hook up a scanner and see what is going on.

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[denhamt1983]

Intermittent, mostly under heavy load? I'd start with the EGR system. There's plenty of other possibilities though, PO may have replaced the fuel pump, but maybe it's not a quality unit, or maybe the tank wasn't cleaned when the new one was installed. Maybe he didn't replace the filter. Could be a vacuum leak, or fuel pressure issue. Best way to tell us hook up a scanner and see what is going on.

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Thanks for the reply, I check with PO and it's true he didnt replace anything else but the pump. I'll get it out to scan that code soon as I can, and will definitely start with the EGR

 

[RawbDidIt]

Thanks for the reply, I check with PO and it's true he didnt replace anything else but the pump. I'll get it out to scan that code soon as I can, and will definitely start with the EGR

EGR issues tend to show up with poor power and throttle response while warm, or with vacuum problems, depending on how it is failing. Should present a code either way, but code may be intermittent if it's just sticking. Also causes hard start condition, but usually runs better after it starts pulling info from o2 sensors. You'll also see it show up in your short term fuel trim while it's happening, but only in your long term fuel trim while it's acting correctly.

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[HotWheelsBurban]

If the throttle position sensor hasn't been replaced within the last couple years, that's kind of how it acts when it's going bad. Look at the egr first, then widen the field of inquiry further. Hope this helps

 

[RawbDidIt]

If the throttle position sensor hasn't been replaced within the last couple years, that's kind of how it acts when it's going bad. Look at the egr first, then widen the field of inquiry further. Hope this helps

Had no clue the TPS would act that way, good to know (figured it was like most sensors, it works up until it doesn't). Only takes 5 minutes to test with a multimeter and a couple of needles, may as well add it to the list.

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[HotWheelsBurban]

Had no clue the TPS would act that way, good to know (figured it was like most sensors, it works up until it doesn't). Only takes 5 minutes to test with a multimeter and a couple of needles, may as well add it to the list.

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Mine croaked pretty much all at once. Was starting the truck (last summer when dealing with the hard start/Passlock issues) and trying to keep it running, and the idle kept fluctuating radically. Normally it starts running at 1000rpm then goes down to 600. Called my cousin who's a retired fleet mechanic and used to have 91 eclb pickup, barely had the barest symptom description out, and he said most likely that's what it was. Replaced it and it was probably the original one. Then a few days later the idle air control valve went out too, was warned by another mechanic friend that would likely happen. Runs fine ever since.

 

[HotWheelsBurban]

If it was just that the truck doesn't want to start when hot, then I would look at starter and cables. But since it doesn't want to run when it's hot, it's more likely a fuel, emissions or sensor acting up issue.

 

[MurderSheWrote]

Hi, first time OBS owner, longtime fan. 1997 K1500 Suburban 5.7L, 250000 miles. Had an issue yesterday that I could use a hand with. I've owned the truck for about 2 months now and had a couple issues with hard starts, like if I ran a bunch of errands then let it sit for 30 mins or so would be pretty tough to get started, worse on a full tank it seemed. Went away after driving it for a couple of weeks, tho, so chalked it up to PO leaving it parked for a while before I bought it. Had a similar problem after a 2 or so hour drive once, but not so bad and once it started no problem.

Yesterday we took her on a camping trip, fully loaded and full tank of gas. Drove about 30 miles/1 hour to where our offroad part of the trip started, crossing one minor mountain pass on the way, all good. Drive about 10 miles back offroad, easy forest service road level stuff. Get to going up the first real hill of this part, moderately steep, and had to stop on the incline to go scout a snow situation up ahead and while I was gone my wife says it just went from running perfect to sputtering, then quickly died. When I reached the truck it was dead, and did the whole hard start thing, but was a PAIN to keep running, just constantly cutting off. Got it turned around, and coming back down cut up a little, but eventually smoothed out and did fine. Cut up a little at highway speed after pulling the mountain pass again, but eventually chilled out and did the last 20 miles or so to town no issues

The PO says he replaced the fuel pump within the last 6 months or so, so it SHOULD be good. I did get a service engine light, but get one intermittently anyway from an exhaust leak so could just be that. Any advice on where to start troubleshooting? Thanks a ton!

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I had almost an identical problem. You are on the right track questioning fuel delivery but you need to look under the air intake. I believe your fuel spider has gone bad. The original spider is single port injection. The new replacements are multi port injection. I replaced mine back in 2016. It took a couple hours and was not only a fix but a great upgrade. I have attached a picture of the old busted SPI spider and a couple pics of the new hotness MPI spider installed.

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[TacosnBeer]

Haha - "the new hotness" - Men in Black! Love the reference.